v3.26.1
SHAREHOLDERS' EQUITY - Schedule of Components of Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Accumulated Other Comprehensive Income (Loss)    
Pre-tax amounts:    
Unrealized pension actuarial gain on defined benefit pension plans $ 30,123 $ 49,401
After-tax amounts:    
Unrealized pension actuarial gain on defined benefit pension plans 30,233 44,964
Unrealized pension actuarial gain on defined benefit pension plans    
Pre-tax amounts:    
Unrealized pension actuarial gain on defined benefit pension plans 4,546 3,336
After-tax amounts:    
Unrealized pension actuarial gain on defined benefit pension plans 5,404 4,470
Unrealized gain on available-for-sale debt security    
Pre-tax amounts:    
Unrealized pension actuarial gain on defined benefit pension plans 0 383
After-tax amounts:    
Unrealized pension actuarial gain on defined benefit pension plans 0 296
Foreign currency translation adjustment    
Pre-tax amounts:    
Unrealized pension actuarial gain on defined benefit pension plans 25,577 45,682
After-tax amounts:    
Unrealized pension actuarial gain on defined benefit pension plans $ 24,829 $ 40,198